AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Theoretical Modeling of Aerosol Lifetimes in a Rotating Drum Aerosol Chamber
MATTHEW BROWN, Steven Cevaer, Erin M. Durke, Suresh Dhaniyala, Clarkson University
Abstract Number: 457 Working Group: Instrumentation and Methods
Abstract Understanding the fate of airborne particles in the atmosphere requires knowledge of their long-term transformation on exposure to different environmental effects such as gases, sunlight, etc. Often such studies have involved particle measurements in large-volume chambers with controlled environments, where the life-times of large particles are often limited to a few hours. For longer term measurements of a wide-range of particle sizes, we investigate the usage of a rotating-drum aerosol chamber, as first proposed by Goldberg (1958). In a rotating drum, Gruel el al. (1987) theorized that a steady-state balance between gravity-induced settling and centrifugal forces resulted in an optimal drum rotation rate as a function of particle size. The method was further explored and built upon by Asgharian and Moss (1992), accounting for transient particle loss due to gravity at extremely low rotation rates (~1e-3 rpm). In revisiting these calculations with numerical simulations, we determine that calculations of Asgharian and Moss (1992) do not accurately capture particle loss in the first rotation of the drum. We derive a new theoretical approach to accurately predict the motion of the particle population within the drum as a function of particle size, drum rotation speed, and rotation time. The new model allows for the calculation of the real-time changes in aerosol size distributions within a rotating drum.